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Research in marine Spanish waters are focused on several actions to achieve an effectively management on protected areas, with the active participation of the stakeholders and research as basic tools for decision-making. Among these actions, there is one about the knowledge and control on NIS. One of its objectives is the creation of NIS factsheets, which are going to be added to the National Marine Biodiversity Geographical System (GIS) providing complementary information about taxonomic classification, common names, taxonomic synonyms, species illustrations, identification morphological characters, habitat in the native and introduced regions, biological and ecological traits, GenBank DNA sequences, world distribution, first record and evolution in the introduced areas, likely pathways of introduction, effects in the habitats and interaction with native species, and potential management measures to apply. The database will also provide data for (1) the European online platforms, (2) the environmental assessment for the Descriptor 2 (D2-NIS) of the EU Marine Strategy Framework Directive (MSFD), as well as (3) supporting decisions made by stakeholders. It is the result of extensive collaboration among scientist, manager’s and citizen science in the Spanish North-Atlantic, South-Atlantic, Gibraltar Strait-Alboran, Levantine-Balearic and Canary Islands marine divisions, providing an updated overview of the spatial distribution of relevant extended and invasive NIS of recent and established NIS introduced by maritime transport and aquaculture pathways, as well as on cryptogenic or native species in expansion due to the climatic water warming trend.

The detection of invasive species is commonly challenging in marine environments, often related with the insufficient taxonomic knowledge of the local diversity. Using DNA sequences in diversity surveys and their phylogenetic analysis can assist us to clarify the native or introduced origin of some species. We applied this approach to study the red algae Aphanocladia stichidiosa. It was originally described in the Mediterranean (1955), later recorded in Portugal (1960), the Canary Islands (1986), the northwestern Spain (1990) and the Azores (2012). Unexpectedly, our diversity surveys in Australia revealed its presence in Victoria in 2015, finding that European and Australian specimens had identical DNA sequences (rbcL gene) and suggesting that it is introduced in one of the regions. Phylogenetic analysis resolved A. stichidiosa in a highly supported clade with species restricted to the southern hemisphere, mainly from Australia. Accordingly, we conclude that A. stichidiosa is native from Australia, although it has never been recorded there before, and that it represents a relatively old introduction in Europe. In both native and introduced regions, it is frequent in algal turfs, a type of assemblage composed by a carpet of small, morphologically similar species whose identification is often difficult. The type of growth of this species explains the absence of previous records in Australia, where the number of taxonomists studying this assemblage is lower than in Europe. Sequential reports of A. stichidiosa in different European regions suggest that it is expanding its distribution, as well as its abundance is increasing. The invasive character of this species needs to be determined yet, and its small size should not lead to underestimate its potential harmfulness. In the current context, in which kelp forests are globally declining and algal turfs are expanding, this species might play a relevant role in the transformation of the European marine ecosystems.

Prokaryotes play an important role in biogeochemical cycling in marine ecosystems, but little is known about their diversity and composition, and it’s even less understood how they may contribute to the ecological functioning of highly variable coastal areas affected by upwelling. Between May 2016 and May 2018, we carried out 26 one-day samplings in the temperate northwestern Iberian upwelling system to investigate the temporal patterns of variability for prokaryotic abundance, diversity and community composition by combining flow cytometry and 16S RNA high- throughput sequencing. A marked seasonality was found for prokaryotic abundance, peaking during summer upwelling and relaxation season (≈May to September), when extracellular release of organic matter from phytoplanktonic blooms is a significant process, and decreasing in downwelling events (≈October to April). Those downwelling conditions, characterized by deeper mixed layers and a homogeneous water column, favored a higher abundance of the archaeal groups, Marine Group II (Euryarchaeota) and Nitrosopelagicus (Thaumarchaeota), as well as of Marinimicrobia bacterium (SAR406 clade) and the group Bacteria_Others. By contrast, upwelling and relaxation conditions characterized by enhanced vertical stratification and hydrographic variability, included a community generally less diverse with core-phylotypes (occurring > 75% of the samples) proliferating, i.e. Flavobacteriaceae (Bacteroidetes), Chloroplast (Cyanobacteria) and Amylibacter (Proteobacteria). Overall, the environmental conditions explained 60% (R2=0.60, AIC=125.64) of the prokaryotic community composition, being temperature, inorganic nutrients, chlorophyll and particulate organic nitrogen the variables that best explained the variation in the prokaryotic community composition (r=0.40). Additional efforts are currently underway on a fine-tuning composition assessment (oligotypes composition from particular core-phylotypes) to study if this variability along the temporal environmental gradient could be associated with the differentiation of ecotypes (oligotype ́s seasonality within particular phylotypes). Overall, the present study provides new insights into the barely explored seasonal niche partitioning of surface prokaryotic community driven by hydrodynamic forcing in an upwelling system, which may support further investigations on the role of bacterioplankton in the biogeochemistry of these ecosystems.

14 pages, 8 figures, 1 table.-- Under a Creative Commons license, Alexandrium minutum blooms generally occur in semi-enclosed sites such as estuaries, harbours and lagoons, where enhanced stratification, restricted circulation and accumulation of resting cysts in the sediment set suitable habitat conditions for the proliferation of this paralytic shellfish poisoning toxigenic species. In the Galician Rías Baixas (NW Iberian Peninsula), according to weekly time-series between 1994 and 2020, blooms of A. minutum were recurrent in small, shallow estuarine bays inside the Rías de Vigo and Pontevedra, but rarely detected, and if so at low concentrations, out of these environments. However, from May to July 2018 it developed as usual in the small inner bays but then spread over both Rías (Vigo and Pontevedra) causing discoloured waters during one month and prolonged harvesting closures. Meteorological conditions during that period (rains / runoff higher than climatological averages, sustained temperature increment and oscillating wind pattern –i.e., series of upwelling-relaxation cycles), fostered optimal circumstances for the development of that extensive and massive proliferation: strong vertical stratification and the alternation of retention and dispersion processes. Simulations from a particle tracking model portrayed the observed bloom development phases: onset and development inside a small inner bay; transport within the surface layer, from these sites towards the interior parts of the Ría; and dispersion all over the embayment. Seedbeds with high concentrations of resting cysts were detected several months after the bloom, which may have favoured flourishment of A. minutum in the following two years, markedly in 2020. The present work contributes to the general understanding of the dynamics of harmful algal blooms (HABs), from which surveillance indicators of the state of marine ecosystems and their evolution can be derived. We hypothesize that the intensity and frequency of A. minutum proliferations in the Galician Rías could increase under projected climate trends, This work was funded by the Spanish national project DIANAS (CTM2017-86066-R, MICINN) and CCVIEO (Instituto Español de Oceanografía). PD-T was supported by the Xunta de Galicia program “Talento Senior” (N° contract 03 IN858A 2019 1630129) with additional funds of the Axencia Galega de Innovacion (agreement GAIN-IEO)

Hace más de 50 años comenzó su andadura el Centro Oceanográfico de A Coruña. Ocurrió en un vetusto local del puerto, y se denominó por aquel entonces como Laboratorio del Noroeste. Durante este medio siglo este centro ha trabajado básicamente en las áreas de la biología pesquera, la acuicultura marina y la oceanografía multidisciplinar, si bien los equipos de investigación han ido evolucionando a lo largo de este tiempo, abriendo o cerrando líneas de trabajo según las circunstancias. A pesar de haber trabajado en todos los océanos del mundo, incluidos el ártico y el antártico, una parte importante de las investigaciones del oceanográfico coruñés siempre han estado centradas en su entorno cercano: el golfo Ártabro. Desde los años ochenta, este centro coruñés monitorea el ambiente pelágico y bentónico de la ría de A Coruña y su plataforma adyacente. Esto supone una valiosísima serie histórica de datos oceanográficos, cuya utilidad quedó de sobra demostrada durante las catástrofes de los petroleros Aegean Sea y Prestige. La idea de crear este libro surgió justo antes del 50 Aniversario del Centro Oceanográfico de A Coruña (1968-2018). Nace con la intención de recopilar y resumir el conocimiento científico en torno a la biodiversidad marina en el ámbito de trabajo más cercano al centro coruñés. Es intención de este libro el servir como publicación de referencia a todo tipo de estudio sobre la biodiversidad y la oceanografía biológica del golfo Ártabro. Para ello nos servimos de la información obtenida directamente del oceanográfico herculino tanto de sus series históricas, como de otros estudios realizados en la zona. Además, la colaboración en materia de pesca de los centros oceanográficos de A Coruña, Vigo, Santander y Gijón permitió aportar a este volumen el capítulo dedicado a las especies desembarcadas por la flota artesanal en la lonja coruñesa. Por otra parte, los especialistas en bentos duro del Centro de Gijón fueron los encargados de elaborar la parte dedicada a este tipo de fauna. Por último, reseñar la inestimable contribución del Grupo de Investigación BioCost de la Universidade da Coruña, auténticos referentes en el conocimiento de la botánica marina de la zona en cuestión.

Eukaryotic plankton is a core component of marine ecosystems with exceptional taxonomic and ecological diversity. Yet, how their ecology interacts with the environment to drive distribution patterns is poorly understood. Here, we use RADIALES time-series (http://www.seriestemporales-ieo.com) metabarcoding to analyze seasonal patterns of eukaryotic plankton diversity and their relationship with environmental factors in an upwelling coastal system. Twenty monthly samples were collected in a station off the Ría de A Coruña (43.42°N, 8.44°W, NW Iberian Peninsula) by filtering seawater through a 3 µm pore size polycarbonate filter. The V4 region of the 18S rRNA was amplified and sequenced using Illumina. Amplicon sequence variants (ASVs) were differentiated using DADA2. Assemblage composition displayed a clear seasonal pattern, so that winter and summer samples showed the highest dissimilarity. Physico-chemical variables (temperature, salinity and inorganic nutrient concentration) explained 54.01% of the structure variability. PERMDISP revealed significant differences in the dispersion of samples within seasons, and winter samples were the most homogeneous. This pattern contrasts with ASVs richness and H’, which peaked in winter and were minimal in spring. These results highlight the importance of transitional periods for diversity dynamics along the seasonal cycle, influencing ecosystem functioning and biogeochemical cycles.

The use of molecular tools in red algal diversity surveys often reveals the existence of undescribed species. Here, we report a new Macaronesian turf-forming red alga in the otherwise mostly Pacific genus Melanothamnus Bornet & Falkenberg. This new taxon, Melanothamnus macaronesicus Rodríguez-Buján & Díaz-Tapia, sp. nov. is described based on morphological and molecular (rbcL gene) evidence. Morphologically, it differs from other Melanothamnus taxa by a combination of characters that includes its decumbent habit with an extensive system of prostrate axes, small size (≤2.5 cm), four ecorticate pericentral cells, unbranched to once-branched trichoblasts and spermatangial branches formed on the first dichotomy of trichoblasts that have a sterile apical cell. Molecularly, this new species differs from its congeners by sequence divergence ≥3.3% in the rbcL gene. Current known distribution of M. macaronesicus Rodríguez-Buján & Díaz-Tapia, sp. nov. is restricted to Macaronesia, suggesting that it could be endemic to this archipelago. Our findings suggest that endemicity among red algae might be more common than previously thought in this bioregion, particularly among easily overlooked turf-forming species., Xunta de Galicia (ED481D/2017/011, 03IN858A2019-1630129), 0,395

Algal turfs are ecosystem engineers receiving growing attention in relation to their expansion on temperate reefs as a consequence of global change. However, their species diversity and taxonomy are still poorly understood. Turfs are composed of densely entangled small seaweeds, in which the red algal order Ceramiales is commonly a major component. The advent of classical molecular taxonomy and -omic approaches has revolutionized investigations of seaweed diversity and systematics. These approaches have been applied to the study of the Ceramiales, facilitating the discovery of new species and resolving classification issues. A molecular diversity survey using the rbcL gene and involving the study of ca. 400 specimens of turf-forming rhodomelacean species in Macaronesia detected impressive amounts of newly discovered diversity. A total of 67 species were identified, of which half corresponded to undescribed species presumably endemic to this bioregion. Likewise, the application of molecular species delimitation methods to widely distributed records of Polysiphonia scopulorum (>150 samples collected in Australia, South Africa, southern Europe and Macaronesia) revealed that it is a complex in which 13 species were resolved. These 13 cryptic species range from endemics with narrow known distributions to a species found in all studied regions. At taxonomic levels above species, the use of plastid phylogenomics has produced well-resolved phylogenies that have been applied to the resolution of classification issues in the Ceramiales. These studies illustrate how classical and newer evolving molecular techniques facilitate the understanding of seaweed diversity and systematics, and provide new insights into the complexity of turf assemblages.

Small eukaryotic plankton has been traditionally characterized using conventional microscopy techniques. Current advances in sequencing technologies allow the costeffective study the diversity within microbial plankton based on DNA sequences. This technique has been implemented in the last 15 years for investigating prokaryotic diversity, but its application to unravel the diversity and distribution of eukaryotic organisms is still incipient. Alleged advantages of this approach include the ability of detecting the smaller fraction of the community that trend to be overlooked in microscopy studies, as well as improving the resolution of taxonomic identification for groups whose morphological study is challenging due the paucity of morphological characters. In this study we characterize the diversity of the nano- and microplankton marine communities using microscopy and rDNA sequencing techniques. The aim of this work is to compare results of both techniques, assessing whether rDNA data can provide new insights into the study of the diversity of eukaryotic planktonic communities. Twenty monthly samples were collected in a station off the Ría de A Coruña (NW Iberian Peninsula). Planktonic samples for DNA studies were collected by filtering seawater samples through a 3 μm pore size polycarbonate filter. DNA was extracted, the V4 region of the 18S rRNA was PCR amplified and subsequently sequenced using the High Throughput Sequencing (HTS) platform Illumina. Amplicon sequence variants (ASVs) were differentiated using DADA2 implemented in R. Sequences were aligned against PR2 v4.12.0 and SILVA 132 18S rRNA databases as references. Microscopic identification of plankton taxa (phytoplankton and protozoa) was made using the Uthermöhl technique. In total 1182 ASVs were identified based on rDNA data, which contrasts with only 65 species identified by microscopy. Morphological identifications of eukaryotic plankton was restricted mainly to diatoms, dinoflagellates and ciliates, while rDNA data allowed the detection of additional taxonomic groups (i.e. protist). Some of them were very abundant, such as the algae Cryptophyceae and Mamiellophyceae or the heterotrophs Ascomycota or parasitic Stramenopiles. Therefore, our study further evidenced that DNA metabarcoding is a valuable tool to uncover part of the great diversity within microbial plankton, improving the detection of small eukaryotes.

Hace más de 50 años comenzó su andadura el Centro Oceanográfico de A Coruña. Ocurrió en un vetusto local del puerto, y se denominó por aquel entonces como Laboratorio del Noroeste. Durante este medio siglo este centro ha trabajado básicamente en las áreas de la biología pesquera, la acuicultura marina y la oceanografía multidisciplinar, si bien los equipos de investigación han ido evolucionando a lo largo de este tiempo, abriendo o cerrando líneas de trabajo según las circunstancias. A pesar de haber trabajado en todos los océanos del mundo, incluidos el ártico y el antártico, una parte importante de las investigaciones del oceanográfico coruñés siempre han estado centradas en su entorno cercano: el golfo Ártabro. Desde los años ochenta, este centro coruñés monitorea el ambiente pelágico y bentónico de la ría de A Coruña y su plataforma adyacente. Esto supone una valiosísima serie histórica de datos oceanográficos, cuya utilidad quedó de sobra demostrada durante las catástrofes de los petroleros Aegean Sea y Prestige. La idea de crear este libro surgió justo antes del 50 Aniversario del Centro Oceanográfico de A Coruña (1968-2018). Nace con la intención de recopilar y resumir el conocimiento científico en torno a la biodiversidad marina en el ámbito de trabajo más cercano al centro coruñés. Es intención de este libro el servir como publicación de referencia a todo tipo de estudio sobre la biodiversidad y la oceanografía biológica del golfo Ártabro. Para ello nos servimos de la información obtenida directamente del oceanográfico herculino tanto de sus series históricas, como de otros estudios realizados en la zona. Además, la colaboración en materia de pesca de los centros oceanográficos de A Coruña, Vigo, Santander y Gijón permitió aportar a este volumen el capítulo dedicado a las especies desembarcadas por la flota artesanal en la lonja coruñesa. Por otra parte, los especialistas en bentos duro del Centro de Gijón fueron los encargados de elaborar la parte dedicada a este tipo de fauna. Por último, reseñar la inestimable contribución del Grupo de Investigación BioCost de la Universidade da Coruña, auténticos referentes en el conocimiento de la botánica marina de la zona en cuestión.

Kelps are foundation species that provide important ecosystem services in temperate rocky shores worldwide. Similarly to terrestrial forests, healthy kelp forests are structurally complex as they are often arranged as patches composed by a multi-layered understorey of algae aggregations with different canopy adaptations. Over the last decades, several studies have reported a global kelp forest degradation, turning seascapes dominated by complex forest into structurally simpler mats of low-laying seaweeds. In NW Spain, golden kelp (Laminaria ochroleuca) canopy forests have recently receded within the limits of a MPA. This paradoxical loss inside a MPA allowed us to investigate the consequences of kelp forest collapse for other members of the biotic community, using nearby healthy kelp forest outside the MPA as a control. To assess these changes, four degraded sites within the MPA and four healthy kelp forest in nearby areas were sampled year round to assess the seasonal dynamics of understorey algae. Healthy and degraded kelp reefs had significantly different understorey assemblage compositions. However, unlike our expectations, these differences had little to none impact on the richness and diversity of the understorey assemblage. Moreover, understory differences were only perceptible when the assemblages were compared at the lowest taxonomic resolution (species). Unlike other studies, comparisons based on functional groups (canopy, sub-canopy, turf and crust) failed to detect any significant difference between healthy and degraded kelp forest.

Small eukaryotic plankton has been traditionally characterized using conventional microscopy techniques. Current advances in sequencing technologies allow the cost-effective study the diversity within microbial plankton based on DNA sequences. This technique has been implemented in the last 15 years for investigating prokaryotic diversity, but its application to unravel the diversity and ecology of eukaryotic organisms is still incipient. In this study we analyze the diversity of the diatoms and dinoflagellates in the marine communities using rDNA sequencing techniques, as well as the taxonomic resolution provided by the V4 region of the 18S rRNA gene. Twenty monthly 6L seawater samples for DNA metabarcoding were collected and filtered through 3 μm polycarbonate filter in a station off the Ría de A Coruña (NW Iberian Peninsula). DNA was extracted, the V4 region of the 18S rRNA was PCR amplified and subsequently sequenced using the High Throughput Sequencing (HTS) platform Illumina. Amplicon sequence variants (ASVs) were differentiated using DADA2 implemented in R. Sequences were aligned against PR2 v4.12.0 and SILVA 132 18S rRNA databases as references, as well as studied using BLAST and phylogenetic trees. Sequence-based taxonomic approach found 128 and 416 metabarcodes corresponding to diatoms and dinoflagellates, respectively. Sequences had limited resolution at species or even genus level, and overall the taxonomic resolution of diatoms was substantially higher than those of dinoflagellates.